GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B2545 00: Backup Lamps Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Backup Lamps Voltage Supply

B2530

1

1

--

1. Backup Lamps Inoperative

Circuit/System Description

When the PRNDL is placed in the REVERSE position, a signal is sent to the body control module (BCM). The BCM then applies voltage through the backup lamps voltage supply circuit to the left and right backup lamps.

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

DTC B2545 is set either when the backup lamps supply voltage circuit is shorted to ground or opened, or if the CHMSL/Bkup fused voltage supply circuit to the BCM is shorted to ground or opened.

Action Taken When the DTC Sets

The backup lamps will not illuminate.

Conditions for Clearing the DTC

    • This DTC will clear on current status after the condition for setting the fault is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • History DTCs can be cleared using a scan tool.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

  1. Perform a visual inspection for loose or poor connections at all related components.
  2. Install a scan tool.
  3. Turn the ignition to the ON position, with the engine OFF.
  4. With a scan tool, select light test and command the backup lamps ON and OFF.

Circuit/System Testing

  1. Place the PRNDL in to the PARK Position. Disconnect both tail lamp assemblies and the inside rearview mirror. Clear the DTC. Using a test lamp connected to ground probe the backup lamps voltage supply circuit at the tail lamps.
  2. If the test lamp illuminates, test for a short to ground or open in backup lamps voltage supply circuit. If all circuits/connections test normal, replace the BCM.
    If the test lamp illuminates, test for a short to ground or an open in the CHMSL/DIMR fuse voltage supply circuit. If all circuits/connections test normal, replace the BCM.
  3. Connect one of the tail lamp assemblies and test for the DTC. If the DTC resets replace that tail lamp assembly.
  4. If tail lamps test normal, replace the inside rearview mirror.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Tail Lamp Replacement
    •  Inside Rearview Mirror Replacement
    •  Control Module References for BCM replacement, setup, and programming